1. Field of the Invention
This invention relates to an image forming method and an image forming apparatus which are used in printers, copying machines and so forth.
2. Description of the Related Art
In conventional image forming apparatus such as printers and copying machines, techniques such as ink-jet recording, thermal transfer and electrophotography are used. In particular, when used to form images at a high speed and in a high minuteness, apparatus employing electrophotographlc techniques are widely used.
Electrophotographic systems, however, have a complicated process and require high-voltage power sources for their charging assemblies. They also have had problems on environment, e.g., the generation of ozone due to corona discharge. In addition, they require a large energy to fix toners, and hence have also had a problem of a large power consumption.
To solve these problems, as disclosed, e.g., in Japanese Patent Application Laid-open No. 8-156401, an image forming method is proposed in which a polar reversible medium capable of reversible hydrophilic-hydrophobic conversion is provided on the surface of a drum and is selectively hydrophilic-hydrophobic switched by exposure (irradiation with light) or heating to control the adhesion of liquid ink. According to this method, the liquid ink to caused to selectively adhere to the drum surface in accordance with image information without use of electric fields, and hence the problems in electrophotographic techniques can be solved.
Since, however, the polar reversible medium is used in the above image forming method in order to form images by selectively hydrophilic-hydrophobic changing the drum surface, there has been a problem that the medium tends to deteriorate as a result of repeated use and may become not achievable of the desired properties because of changes with time. Also, the polar reversible medium capable of reversible hydrophilic-hydrophobic conversion has a narrow range of materials selection, and there has been a possibility of a high cost. Since also the hydrophllic-hydrophobic conversion of the surface is utilized, there has been a possibility that the system tends to be affected by drum surface contamination or adhesion of developer to become unstable.